MX Record (Mail Exchanger)

An MX (mail exchanger) record lists the hostnames of the servers that accept email for a domain, each with a numeric preference. Sending servers look up the MX records for the recipient's domain and try the lowest preference value first.

Why it matters

Without valid MX records, mail to your domain bounces or, in some cases, is delivered to the domain's A record as a fallback. A wrong record silently sends your mail to the wrong provider. Multiple records with different preferences give you backup servers; equal preferences share load.

Example

example.com.  3600  IN  MX  10  mx1.mailhost.example.
example.com.  3600  IN  MX  20  mx2.mailhost.example.

Mail goes to mx1 first and falls back to mx2 if mx1 is unreachable. Check with dig +short example.com MX.

Common mistakes

• Pointing an MX at an IP address. The target must be a hostname that has an A or AAAA record.
• Pointing an MX at a CNAME. Mail standards say the target must be a canonical name, and some senders refuse to deliver.
• Keeping old provider MX records after migrating, so some mail still lands in the old mailbox.
• Assuming a bigger number means higher priority. It is the opposite.

Related

• SPF
• Email bounce
• A record
• Guide: MX records explained
• Tool: MX lookup

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.